Completing the last link in the Transcontinental Railroad with a spike of gold was the brainchild of David Hewes, a San Francisco financier and contractor. The spike had been manufactured earlier that year especially for the event by the William T. Garratt Foundry in San Francisco. A special tie of polished California laurel was chosen to complete the line where the spike would be driven. The golden spike was made of 17.6-karat(73%) copper-alloyed gold, and weighed 14.03 troy ounces. It was dropped into a pre-drilled hole in the laurel ceremonial last tie, and gently tapped into place with a silver ceremonial spike maul.

On May 10, in anticipation of the ceremony, Union Pacific No. 119 and Central Pacific No. 60 (better known as the Jupiter) locomotives were drawn up face-to-face on Promontory Summit, separated only by the width of a single tie. It is unknown how many people attended the event; estimates run from as low as 500 to as many as 3,000; government and railroad officials and track workers were present to witness the event.

A second golden spike, identical to the one from the ceremony, was cast and engraved at the same time. It was held, unknown to the public, by the Hewes family until 2005. This second spike is now on permanent display, along with Thomas Hill's famous painting The Last Spike, at the California State Railroad Museum in Sacramento.

With the locomotives drawn so near, the crowd pressed so closely around Stanford and the other railroad officials that the ceremony became somewhat disorganized, leading to varying accounts of the actual events. Contrary to the myth that the Central Pacific's Chinese laborers were specifically excluded from the festivities, 8 Chinese laid the last rail, and three of these men, Ging Cui, Wong Fook, and Lee Shao, lived long enough to also participate in the 50th anniversary parade. At the conclusion of the ceremony, the Chinese participating were honored and cheered by the CPRR officials.

To drive the final spike, Stanford lifted a silver spike maul and drove the spike into the tie, completing the line. Stanford and Hewes missed the spike, but the single word "done" was nevertheless flashed by telegraph around the country. In the United States, the event has come to be considered one of the first nationwide media events. Immediately afterwards, the golden spike and the laurel tie were removed and replaced with a regular iron spike and normal tie. At exactly 12:47 p.m., the last iron spike was driven, finally completing the line.